Aroma chemicals, especially fragrances are of great interest especially in the field of cosmetics and cleaning and laundry compositions. Fragrances of natural origin are mostly expensive, often limited in their available amount and, on account of fluctuations in environmental conditions, are also subject to variations in their content, purity etc. To circumvent these undesirable factors, it is therefore of great interest, by way of example, to chemically modify readily available natural substances, e.g. readily available fragrances of natural origin, to create substances, which have organoleptic properties that resembles more expensive natural fragrances or which have novel and interesting organoleptic profiles. Such “semi-synthetic” substances can, by way of example, be used as substitutes for purely natural substances on account of their odor, where substitute and natural substance do not necessarily have to have a chemical-structural similarity.
However, since even small changes in chemical structure may bring about massive changes in the sensory properties such as odor and also taste, the targeted search for substances with certain sensory properties such as a certain odor is extremely difficult. The search for new fragrances and flavors is therefore in most cases difficult and laborious without knowing whether a substance with the desired odor and/or taste will even actually be found. There is a constant need for novel aroma chemicals with advantageous sensory properties.
Ylang-ylang oil has a long history of fragrance and food flavoring use. Ylang-ylang oil is obtained by steam distillation of the flowers of the Ylang-Ylang tree, Cananga odorata. The oil from ylang-ylang is widely used in perfumery for oriental themed perfumes (such as Chanel No. 5). The main aromatic components of ylang-ylang oil are benzyl acetate, linalool, p-cresyl methyl ether, and methyl benzoate, responsible for its characteristic odor. Ylang-ylang oil or p-methyl-cresylether have been used to impart the characteristic, desirable note (the so called “ylang ylang note”) to many compositions, such as e.g. perfume compositions, body care compositions, hygiene articles, household cleaning compositions, textile detergent compositions, foods and food supplements. Due to the limited availability of the natural source of the ylang-ylang oil, but especially due to the toxicological concerns of p-methyl-cresylether, there is a constant need for an aroma chemical, which can impart a ylang-ylang note to a composition and which at the same time is suitable for compositions that are in direct contact with the human skin.
Rupe et al. (Helevetica Chimica Acta, 1931, 14, 701-708) disclose on page 702, formula III 1-[4-methylcyclohexen-1-yl]ethanone without any information regarding the stereochemistry. From the described method of synthesis of the substance of formula III it is chemically compulsory, that the substance of formula III can only be a racemic mixture. Rupe et al. on page 704 attribute a “fine, strong, roselike odor” to this racemic mixture. Rupe et al. does not provide any hint or information that 1-[(4R)-4-methylcyclohexen-1-yl]ethanone can be used to impart a ylang-ylang note to a composition.
Dolby et al. (J. Org. Chem, 29, 2306, 1964) on bridging columns of page 2306 to page 2307 describe the preparation of 1-acetyl-4-methylcyclohexene by ozonolysis of the dimer which is formed during acid catalyzed dimerization of (+)-Citronellal. 1-[(4R)-4-methylcyclohexen-1-yl]ethanone itself is disclosed in Taber et al. (J. Org. Chem., 44, No 3, 450-452, 1979) page 450, formula 11. Neither reference discloses the use of 1-[(4R)-4-methylcyclohexen-1-yl]ethanone according to the invention.